1. Field of the Invention
Method and apparatuses consistent with the present invention relate to using the internet to control a device connected to a universal plug and play (UPnP) home network, and more specifically, controlling a device connected to a UPnP home network using a polling-based notification service provided by the Consumer Electronics Association (CEA) 2014 standard.
2. Description of the Related Art
Computing technology has been recently applied to various devices, and as such, cheap and universal networking techniques are appearing and being used. For example, various devices used in houses, such as refrigerators, TVs, washing machines, person computers (PCs), and audio players, are connected to a network, so that user convenience is increased. In order to achieve this networking, a universal plug and play (UPnP) standard has been proposed. UPnP is a standard that allows devices, such as a PC, a peripheral device, an intelligent home appliance, and wireless equipment, to automatically recognize each other using the Internet and a web protocol when they are connected to a network. When UPnP is used and a user adds a device to the network, the device is automatically installed without manual configuration, receives a TCP/IP address, and uses a discovery protocol based on the Internet HTTP in order to inform the other devices of the existence of the additionally connected device. For example, when a camera and a printer have been connected to a network and a picture is to be output from the printer, a button of the camera is pressed, and the camera sends a discovery request signal to the network in order to search for an available printer on the network. Then, in response to the discovery request signal, the printer sends its location in Uniform Resource Locator (URL) format to the camera. The camera and the printer may use an extensible markup language (XML) as a common language or determine a way of communicating with each other by protocol negotiation. When the common language for communication is determined, the camera is able to control the printer to print out a desired picture. In particular, the UPnP device architecture version 1.0 enables home appliances within a UPnP home network to be peer-to-peer networked on the basis of a decentralized and open networking structure instead of being under a centralized control. In this case, the UPnP specifies that standard networking technologies, such as IP and HTTP, are used as technical components of the decentralized and open networking structure so that the technical components operates independently of an operating system, a platform, and a transmission medium.
Generally, UPnP device architecture version 1.0 uses a multicasting method in order to discover a device, and thus it is impossible to discover and control devices existing on other networks. When a UPnP home network is implemented as a virtual private network (VPN) due to lack of IPv4 addresses, a UPnP device within the UPnP home network is unable to access via the Internet unless undergoing network address translation (NAT). Although the UPnP device within the UPnP home network is able to access via the Internet using a photo-mapping method, a separate UPnP Internet gateway device (IGD) is required.
For these reasons, when a UPnP home network device is constructed according to the UPnP version 1.0, it is impossible to control a device connected to a UPnP home network that is constructed using a VPN.